Iran's military said it had shot down the US drone near the country's eastern border. Photograph: Ethan Miller/Getty Images

Iran's armed forces have shot down an unmanned US spy plane that violated Iranian airspace along its eastern border.

An unidentified military official quoted by the official Irna news agency on Sunday warned of a crushing response to any violations of Iranian airspace by US drone aircraft.

"An advanced RQ170 unmanned American spy plane was shot down by Iran's armed forces. It suffered minor damage and is now in possession of Iran's armed forces," Irna quoted the official as saying.

No further details were given.

Later a spokesman for Nato's International Security Assistance Force in Afghanistan said a surveillance drone flying over western Afghanistan had gone out of control late last week and may be the one Iran said it had shot down over its own airspace. "The UAV to which the Iranians are referring may be a US unarmed reconnaissance aircraft that had been flying a mission over western Afghanistan late last week. The operators of the UAV lost control of the aircraft and had been working to determine its status," an ISAF statement said.

Iran is locked in a dispute with the US and its allies over Tehran's alleged nuclear programme, which the west believes is aimed at developing nuclear weapons. Iran denies the accusations, saying the programme is designed to generate electricity and produce isotopes for medical use.

Tehran said in January it had shot down two other unmanned spy planes over its airspace which were operated by the US.

Iran itself has focused part of its military strategy on producing drones, both for reconnaissance and offensive purposes.

It announced three years ago that it had built an unmanned aircraft with a range of more than 600 miles, far enough to reach Israel.

The Iranian president, Mahmoud Ahmadinejad, unveiled Iran's first domestically built unmanned bomber in August 2010, calling it an "ambassador of death" to Iran's enemies.